1. Field of the Invention
This invention relates to a lightweight ring laser gyro, particularly one mounted in an aerogel housing.
2. Prior Art
Currently, in prior art ring laser gyros (RLGs) frame and mirror material design, ultra low expansion (ULE) glass or glass ceramic is employed. Ring laser gyros (RLGs) are used for measuring rotation in inertial space about the input axis. When combined with three accelerometers, such three-axis RLG yields an inertial sensor assembly which may be directly applied to navigation, guidance and control systems for vehicles and positioning systems, eg. for oil drilling bits. Such materials have densities of approximately 2200 mg/cc.
Such prior art RLGs employ laser beams in a Sagnac interferometer (SIF) to count fringe lines and translate rotational movement into angular displacement by means known in the art. A typical small prior art three-axis system 10 is shown in FIG. 1. The prior art system uses three relatively heavy ULE glass blocks, 12, 14 and 16 mounted on separate sides of a rectangular housing 18, per FIG. 1, which blocks are positioned as orthogonal planes on the x,y and z axes. Each block has a triangular laser path 20 (more fully discussed below) cut therein to measure rotation of a body (to which it is mounted) on one of the above three axes.
That is, the y axis, for example, is the input axis to laser triangle 20 of block 14, as shown in FIG. 1. The input axis is a mathematical construct, orthognal to the plane of such laser triangle as further discussed below. Angle readings from the three glass blocks give a combined reading of the rotation of such body (eg. a vehicle) on all three axes. Such prior art RLG is relatively large, cumbersome and heavy which limits the size and/or number thereof according to launch payload constraints for, e.g. space vehicles. Accordingly, there is need and market for lighter weight RLG systems than have been previously available.
There has now been discovered a light-weight system of greatly reduced weight and in certain embodiments, considerably more compact than prior art RLGs. In some embodiments, the RLG system of the invention combines three othogonal laser planes or triangles in one housing or block, for a significant savings in weight and size of such RLG system of the present invention.